The present disclosure relates to a high voltage semiconductor device including a drift region.
A Metal Oxide Semiconductor Field Effect Transistor (MOSFET) may have relatively high input impedance compared to a bipolar transistor, providing a relatively large power gain and/or a relatively simple gate driving circuit. Further, the MOSFET may be a unipolar device having substantially no-time delay which may result from minority carrier storage and/or recombination while being turned off. The MOSFET may be applied to switching mode power supply devices, lamp ballasts, motor-driving circuits and the like. For example, a DMOSFET (Double Diffused MOSFET) manufactured by using a planar diffusion technology is generally used.
A lateral double diffused metal oxide semiconductor (LDMOS) device may be applied to a VLSI process due to its relatively simple structure. Particularly, the LDMOS device may have relatively improved electrical characteristics compared to a vertical DMOS (VDMOS) device. For example, Korean Laid-Open Patent Publication No. 10-2010-0056101 discloses a LDMOS device including an n-type RESURF (reduced surface field) region, a p-type first impurity region and an n-type second impurity region, which are formed under a gate electrode structure, so as to improve breakdown voltage and reduce on-resistance (Rsp). Further, Korean Laid Open Patent Publication No. 10-2006-0077006 discloses a high voltage semiconductor device including a conventional Double Diffused Drain (DDD) structure.
FIG. 1 is a cross-sectional view illustrating a conventional high voltage semiconductor device including a DDD structure.
Referring to FIG. 1, a conventional high voltage semiconductor device 100 includes a gate electrode structure 110 disposed on a well region 104 of a substrate 102, a source region 120 disposed in the well region 104 to be adjacent to one side of the gate electrode structure 110, a drift region 130 disposed in the well region 104 to be adjacent to another side of the gate electrode structure 110, a drain region 140 disposed in the drift region 130, and a device isolation region 106 disposed on one side of the drain region 140.
The drift region 130 is used to improve the breakdown voltage of the high voltage semiconductor device 100. However, when the size of the drift region 130 is increased to further improve the breakdown voltage of the high voltage semiconductor device 100, the leakage current to other adjacent semiconductor devices may be increased. Particularly, the electrical resistance of the drift region 130 may be increased, and the on-current of the high voltage semiconductor device 100 may be reduced.
Further, when the size of the device isolation region 106 is increased to reduce the leakage current, the overall size of the high voltage semiconductor device 100 may be increased.